Caterpillar-style premium aftermarket track-shoe bolt. Part reference 6T8520. Size/application: Track Bolt Master D11 N/R. Use the matching model-specific track nut; confirm the exact nut reference for the listed undercarriage. High-strength undercarriage fastener for the specified track-shoe assembly. Brand compatibility: Caterpillar and premium aftermarket systems built to the matching Caterpillar specification. Match thread, shank length and machine model before installation.